Three recent studies having reported an association between low birth weight and infectious disease mortality were evaluated with regard to six methodological standards for scientific validity. At most, only half of the standards were completely fulfilled in any study. Overall, the studies were particularly deficient with regard to description of methods of ascertainment of eligibility, achievement of nondifferential ascertainment of birth weight and of mortality, demonstration of nondifferential acquisition of diagnostic data regarding cause of death, and provision of explicit and unbiased cause of death classification. Our review of the published literature regarding low birth weight and infectious disease mortality demonstrates significant methodological limitations with all of these studies. This review also highlights the need for further research in this area in order to provide credible evidence regarding the presence and strength of a potential relationship between low birth weight and infectious disease mortality.